1. Field of the Invention
The present invention relates generally to separating machines for receiving pieces of bony meat or fish, or other food materials containing relatively soft and relatively hard components, and for separating the meat and other soft components from the bone and other hard components. As applied to bony meat or fish, such machines are often referred to as deboning machines.
2. Related Art
In many machines for separating relatively soft and relatively hard components from material having both the relatively soft and relatively hard components to be separated, the material having both the relatively soft and relatively hard components, such as bony pieces of meat or fish where the relatively soft meat is to be separated from the relatively hard bone, are fed into a separator housing having a generally cylindrical screen with a multitude of small perforations therein. A pressure auger or conveying screw is rotatable within the screen. The conveying screw develops pressure which presses the meat and/or other soft materials through the perforations of the screen, while the particles of bone and/or other hard materials are propelled by the conveying screw to the discharge end of the separator housing from which the hard particles are discharged through a restricted orifice formed by an annular valve which maintains pressure in the separator housing.
A close clearance should be maintained between the outer edges of the screw flights of the conveying screw and the inside surface of the screen. The desired close clearance may be such as to allow creation of a thin filter mat between the conveying screw and the inside surface of the screen, for example as taught by McFarland U.S. Pat. Nos. 3,739,994 and 4,566,640. Alternately, the desired close clearance may provide for the outer edges of the screw flights to bear closely against the inside surface of the screen so that no filter mat is created and so that the outer edges of the screw flights form a continuous spiral blade bearing closely against the inside surface of the screen to effect a strong cutting action relative to the perforations along the length of the screen, thereby avoiding the creation of a filter mat, for example as taught by McFarland U.S. Pat. No. 5,580,305. In either case, since the outer edges of the screw flights are subject to wear as the machine is used, it is important to be able to adjust and maintain the desired clearance between the outer edges of the screw flights of the conveying screw and the inside surface of the screen. When the screen is tapered to form a frusto-conical shape and the outer edges of the screw flights are similarly tapered along the length of the screw, the clearance between the outer edges of the screw and the inner surface of the screen can be adjusted by adjusting the axial positioning of the screw within the screen, for example as shown by McFarland U.S. Pat. No. 5,580,305. However, where the screen and screw flights are not tapered, such adjustment is not available.